Hopefully no one minds, I have a different question related to bugs with this quest. Can anyone confirm that there is a bug related to some people not getting this quest to start at all? I've spent 10 levels (I'm level 20 now) and a month of in-game time waiting for Susanna to get murdered.. and nothing. I've advanced pretty far in the Stormcloak questline, if that has anything to do with it, and I've done numerous quests all over the map. I've spoken to anyone who will mention anything about the murders. After every quest, I fast travel back to Windhelm to see if the murder has happened, and nothing. Many others seem to get it on their second time in Windhelm after not doing much at all. Is it a bug? Am I missing something?
I got a similar problem. I found the real killer, Calixo in the creepy house but he was totally invulnerable. I punched his health down to 0 but he always got up, no quest update.. :/ This quest was totally broken, I had to load a savegame from the time before I started even the 1st stage of this quest! I Lost 10 levels, and now I have to do a lot of quests, adventures again!! I enjoy the game though, so that's not problem but I fear that I will encounter another serious bug like this and I'll loose a lot of gaming hours again :'( I wonder if Bethesda will ever fix things like that... They provided a 0 day patch but there are still bugs

Originally I used lockpicks to get into that house, and by doing so I skipped a quest stage, when you have to get the proper key from an old women. Most likely this ruined the quest line, so I got stuck bcs the killer remained an "essential" NPC.
My solution was to load the previously mentioned savegame, and start the quest again, from 0. I read the UESPwiki article about this quest and followed every single instructions step by step!!
So finally I was able to kill Calixo and to complete the quest.
Is there a topic about all known bugs / bugged or easily glitchy quests???